JP2003072068A - Ink jet recording head and ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head having a configuration in which a high-density nozzle arrangement is realized in a matrix arrangement head, a full acoustic capacity is secured for a plurality of branching channels by a simple constitution inexpensively, an ink supply shortage is prevented by suppressing acoustic crosstalks, and a high-speed ink refilling operation can be realized. SOLUTION: An ink pool 17 of the ink jet recording head 26 is provided with a main channel 16 communicating with an ink supply port 19, and the plurality of branching channels 15 branching from the main channel 16. An ejector is provided with pressure chambers 12 communicating with the branching channels 15, pressure generation means for generating pressure waves to ink filled in the ink pressure chambers 12, and nozzles 11 for discharging ink within the pressure chambers 12 contracted by pressure waves. At least one of wall faces constituting the branching channel 15 is constituted of a damper member 18 which is elastically deformed in accordance with a pressure change in the branching channel 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head and an ink jet recording apparatus, and more specifically, an ink jet recording head for ejecting ink droplets from a plurality of ejectors arranged in a matrix, and the ink jet recording head mounted thereon. Inkjet recording apparatus.

[0002]

2. Description of the Related Art The non-impact recording system has features such as high speed, high image quality and low noise, and is currently the mainstream of printers. Among them, inkjet printers that eject ink droplets from multiple nozzles to print characters, graphics, photographs, etc. on recording paper are widely used because of their features such as small size, low cost, and printing of photographic image quality. ing.

The ink jet type recording head is, for example, 24 per color while moving the head in the main scanning direction.
Ink droplets are selectively ejected from a plurality of nozzles such as 300 according to an electric signal based on print data, and the ink droplets are attached to the surface of a recording medium such as recording paper. This recording head can print characters and figures on the recording medium by further combining with the operation of moving the recording medium in the sub-scanning direction orthogonal to the main scanning direction.

In the ink jet recording head as described above, ink is stored in an ink pool commonly provided for a plurality of nozzles, and the ink in this ink pool passes through a narrow inlet provided for each nozzle. Is introduced into the pressure chamber. Furthermore, pressure is generated in the ink in the pressure chamber by pressure generating means such as a piezoelectric element that operates in response to an electric signal, and an ink droplet is ejected from the nozzle. Hereinafter, the ink droplet ejection mechanism including the nozzle, the pressure chamber, the inlet, and the pressure generating means is referred to as an ejector.

An example of the ink jet recording head having the above structure is described in Japanese Patent Application Laid-Open No. 8-58089. 16 and 17 are a sectional view and a plan view, respectively, showing the ink jet recording head described in the above publication.

As shown in FIGS. 16 and 17, the ink jet recording head has a nozzle forming plate 61, an ink pool plate 62, and a diaphragm forming plate 63 having an ink supply diaphragm 63a (corresponding to an inlet), which are sequentially stacked. Sealing plate 64, pressure chamber forming plate 65,
And a pressure plate 66. The pressure generating unit is composed of a pressure plate 66 and a piezoelectric element 67, and applies a voltage control signal between the upper electrode 68a and the lower electrode 68b to generate a pressure wave (acoustic wave) in the ink in the pressure chamber 71. Generate. The plates 61 to 66 form an ink flow path from the ink pool 69 to the nozzle 73 via the ink supply diaphragm 63a, the communication hole 70, the pressure chamber 71, and the ink communication hole 72.

In the ink jet recording head as described above, the pressure generating means composed of the pressure plate 66 and the piezoelectric element 67, and the ejector having the nozzle 73, the pressure chamber 71 and the ink supply diaphragm 63a, As shown in FIG. 17, the ejector array 7 is arranged in a straight line.
Make up 4. In the following, the inkjet recording head with ejectors arranged in a straight line is referred to as a "linear array head".
Call.

In the linear array head using the piezoelectric element as the pressure generating means, there is a problem in realizing a high density arrangement of the ejectors due to the characteristic limit of the pressure generating means and the restriction of the manufacturing technique. In order to arrange the ejectors at high density with the linear array head, it is necessary to narrow the pressure chamber width,
It is necessary to construct an ink jet recording head by an elongated ejector having a large aspect ratio.

However, when the width of the pressure chamber is narrowed in order to realize the high density arrangement of the ejectors, the width of the pressure plate movable region is also narrowed and the flexural rigidity of the pressure plate is increased. Therefore, a sufficient amount of deformation of the pressure plate cannot be obtained, and it becomes difficult to discharge a desired ink droplet amount. Further, although the pressure chamber can be formed by etching, machining, resin molding, or the like, there is a limit to miniaturization of the width of the pressure chamber due to the limit of precision of machining.

In the linear array head using the pressure generating means composed of the pressure plate and the piezoelectric element as described above, due to the performance limit of the pressure generating means and the restriction of the manufacturing technique,
There was a limit of high-density arrangement to substantially 120 lines / inch to 180 lines / inch. In a linear array head, it is possible to double the nozzle density by arranging the ejectors in a zigzag manner, but in that case, there is a new problem that the head size is doubled and the head cost is doubled.

As an ink jet type recording head which solves the above problems, there is known a recording head in which a large number of ejectors having pressure chambers having an aspect ratio close to 1 are arranged in a matrix to achieve high density of nozzles. A recording head having such a structure is disclosed in Japanese Patent No. 2806386 and Japanese Patent Laid-Open No.
-156095 and Japanese Patent Publication No. 10-508808.

In FIGS. 18 and 19, Japanese Patent No. 280638 is shown.
7 shows a main configuration of an ink jet recording head described in Japanese Patent Laid-Open No. Since the nozzles 75 are arranged in a matrix in this recording head, the recording head is hereinafter referred to as a “matrix array head”.

In the above matrix array head, a nozzle plate 82 having nozzles 75 that are sequentially stacked, a distribution plate 83 having an ink supply groove 79 and an ink passage 77,
A cavity plate 84 having a pressure chamber 76 and a branch 81,
And a pressure plate 85. A piezoelectric element 86 is fixed on the pressure plate 85.

In the matrix array head described above, FIG.
As shown in FIG.
Ink supply source (not shown) between each column
A plurality of ink supply grooves 79 communicating with (corresponding to branch flow paths)
Are formed parallel to each other. Furthermore, each communication hole 80
And the branch passage 81 provided for each pressure chamber 76 are connected to form an ink flow path. Such a matrix array head has an advantage that the nozzle density in the sub-scanning direction can be increased without reducing the width of the pressure chamber 76.

By the way, in the ink jet recording head, it is a very important subject to secure a sufficient acoustic capacity in the ink pool.

In the ink jet recording head, due to the propagation of the pressure wave applied to a certain pressure chamber, not only the ink droplets are ejected from the nozzle communicating with this pressure chamber, but also the ink pool communicating with this pressure chamber is discharged. Also, a phenomenon called acoustic crosstalk occurs in which the pressure wave propagates through the inlet. When the pressure wave propagates to another ejector adjacent to the ejector through the ink pool, the ejection state of the nozzles other than the desired nozzle may be adversely affected. When this influence is remarkable, a phenomenon occurs in which a small amount of ink is ejected from the adjacent nozzles other than the nozzles from which ink should be ejected. In order to suppress the adverse effect on the adjacent nozzle due to such acoustic crosstalk, the pressure wave propagating to the ink pool via the inlet is absorbed and attenuated in the ink pool, and the pressure wave is not propagated to the adjacent ejector. It is important to provide the ink pool with a sufficient acoustic capacity.

Further, when the acoustic capacity of the ink pool is insufficient, when the ejection frequency of ink drops is increased, or when the number of nozzles ejecting ink drops at the same time is increased, the ink pool is moved to each pressure chamber. The amount of ink to be supplied is insufficient, and a stable ejection state cannot be obtained.

FIG. 20 is a diagram schematically showing the meniscus operation of the nozzle portion before and after ink droplet ejection. The meniscus 45 that was initially in a substantially flat state (see FIG.
In (a), when the pressure generating chamber is compressed, it moves toward the outside of the nozzle to eject the ink droplet 46 (FIG. 20).
(B)). When ink droplets are ejected, the amount of ink inside the nozzle decreases, so that a concave meniscus 45 is formed (FIG. 20C). The concave meniscus 45 gradually returns to the nozzle opening due to the action of the surface tension of the ink (FIG. 20 (d)), and thereafter, a slight overshoot of the meniscus surface (FIG. 20 (e)) occurs. After repeated vibration such as a concave shape (FIG. 20D), the state before ejection is restored (FIG. 20F). Figure 20
As shown in (c), the drawing position of the meniscus surface with respect to the nozzle surface is defined as y.

FIG. 21 is a graph showing an example of changes in the position of the meniscus immediately after ink ejection. Immediately after ejection (t = 0), a large receding meniscus (y = -60
μm) returns to the initial position (y = 0) while vibrating as shown in this graph. Such a meniscus returning operation after ink droplet ejection is called refill in the present specification, and a time (t) until the meniscus first returns to the nozzle opening surface (y = 0) after ink droplet ejection.
_r ) is called the refill time. The refill time (t _r ) in FIG. 20 is calculated from FIG.
It exists between (e).

In order to continuously eject ink droplets in a stable state, it is important to execute the next ejection after refilling is completed. Further, in order to continuously eject ink droplets in a stable state, it is important that the meniscus shape immediately before the ink droplet ejection is always in a constant state.
For example, when the next ejection is performed in the meniscus state as shown in FIG. 20C before the refill is completed, the ejected ink droplet diameter becomes extremely small, or the normal ink droplet ejection is performed. May become impossible, or air bubbles may be caught from the nozzle surface and discharge may become impossible.

When the next ejection is performed in a state where the meniscus overshoots after ink refilling as shown in FIG. 20 (e), the axial symmetry of the meniscus shape is easily broken, and bubbles are entrained from the nozzle surface to cause non-ejection. There may be cases where In this way, after ejecting ink drops,
Only after a time t _r or more has elapsed, the next ink droplet ejection cannot be performed stably. Therefore, securing a sufficient acoustic capacity in the ink pool to realize high-speed ink supply is an important characteristic parameter that controls the maximum ejection frequency (that is, recording speed) of the inkjet recording head. Also, if the ejector's refill time is not constant, stable continuous ejection cannot be achieved.Therefore, sufficient acoustic capacity must be ensured in the ink pool and ink should be supplied so that there is no difference in refill characteristics between ejectors. It is extremely important to control the shortage.

It is possible to shorten the refill time by reducing the amount of ink droplets to be ejected, that is, to suppress the shortage of ink supply, but in that case, it becomes impossible to obtain a sufficient print density. It is possible to prevent the ink supply shortage by limiting the number of nozzles that are ejected at the same time or by lowering the ejection frequency.
In that case, a sufficient printing speed cannot be obtained.

As described above, in the ink jet recording head, it is extremely important to secure a sufficient acoustic capacity in the ink pool in order to prevent the acoustic crosstalk and the insufficient supply of ink. A linear array head having a pressure buffering means arranged in the ink pool or on the ink pool wall is disclosed in JP-A-59-98860 and JP-A-9-14.
No. 1864 and Japanese Patent Laid-Open No. 1-308644.

Japanese Unexamined Patent Publication No. 59-98860 discloses a linear array head provided with a pressure pulse absorbing member for absorbing a pressure wave in a common ink chamber (corresponding to an ink pool). The pressure absorbing member is composed of a capsule wrapped with a thin film of plastic film, and inside is air,
Contains gas such as water vapor. Japanese Unexamined Patent Publication No. 9-141864
The publication discloses a linear array head in which a pressure absorbing member made of foamed resin or the like is provided in an ink pool. In JP-A-1-308644, a linear array in which a pressure-volume converter of 0.01 mm ³ / atm or more made of an organic material or an elastic material is provided in the ink pool or at a position adjacent to the ink pool. A head is disclosed.

An example in which a part of the wall surface forming the ink pool is composed of a buffer member which is easily deformed is disclosed in Japanese Patent Laid-Open No. 59-429.
No. 64, Japanese Patent Application Laid-Open No. 9-314836, and the like. Japanese Laid-Open Patent Publication No. 59-42964 discloses a drop-on-demand type print head in which a part of the wall surface different from the nozzle surface of the ink pool is composed of a cushioning member made of a flexible film material. JP-A-9-31483
No. 6 discloses a laminated ink jet recording head in which an elastically deformable region is formed on the inner surface of an ink pool. The elastically deformable region is formed inside the ejector, not on the surface layer surface on the nozzle surface side, and is realized by providing a thin portion (recess) made of a metal material on one surface forming the ink pool.

The above-described disclosure examples of the cushioning member and the like are all disclosure examples relating to a "linear array head" in which a plurality of ejectors communicate with a common wide ink pool. As shown in FIG. 17, in the linear array head, since the ink pool 69 can be arranged in a region different from the ejector array 74, the wide ink pool 69 is irrelevant regardless of the nozzle density of the ejector array 74. Have the advantage that they can be placed. Therefore, in the linear array head, although there is a problem in the high density arrangement of the ejectors as described above, by installing the pressure wave absorbing member or the like, it is possible to easily secure a sufficient capacity in the ink pool.

In each of the disclosed examples of the cushioning member and the like, a damper mechanism such as a pressure relaxation means and a thin portion is formed inside the ejector, and a special constituent member and a special working process for forming the pressure damper are used. And requires
The structure was complicated and the processing process was complicated.

[0028]

By the way, the matrix array head has the advantage that the density of the nozzles can be easily increased, but on the other hand, it is necessary to construct the head with a narrow branch flow path. It is difficult to realize a capacity pressure damper. Further, unlike the linear array head, there are a large number of pressure chambers communicating with a plurality of branch flow paths in the head, and as described above, the pressure damper is arranged inside each ejector including the pressure chambers. Then, the structure becomes more complicated than that of the linear array head, the working process becomes more complicated, and the manufacturing cost increases.

In view of the above, the present invention realizes a high-density nozzle array in a matrix array head, ensures a sufficient acoustic capacity for a plurality of branch flow paths at a low cost with a simple structure, and reduces acoustic crosstalk. An object of the present invention is to provide an inkjet recording head configured to suppress ink supply shortage and to realize high-speed ink refilling operation, and an inkjet recording head including such an inkjet recording head.

[0030]

In order to achieve the above object, an ink jet recording head according to the present invention is provided with an ink supply port, an ink pool to which ink is externally supplied through the ink supply port, and a matrix. An ink jet recording head comprising a plurality of ejectors arranged in a line, wherein the ink pool comprises a main flow path communicating with the ink supply port, and a plurality of branch flow paths branched from the main flow path, Each ejector has a pressure chamber communicating with the branch flow passage, a pressure generating unit for generating a pressure wave in the ink filled in the pressure chamber, and a nozzle for ejecting the ink in the pressure chamber compressed by the pressure wave. And at least one of the wall surfaces forming the branch channel is formed of a damper member that elastically deforms in response to a pressure change in the branch channel. To.

The "pressure damper" referred to in the present specification is a general term for a member that constitutes a part of a wall surface and a means for buffering a pressure wave and is extremely easily deformed.

In the ink jet recording head according to the present invention, a matrix array head has a plurality of pressure chambers communicating with a plurality of branch flow passages inside the head, but has a pressure damper inside each ejector including the pressure chambers. A complicated process such as disposition is not required, and the processing process is simplified, which can be expected to reduce costs. In addition, a sufficient acoustic capacity is secured in the branch flow passage without adding a special component member or a processing step such as providing a special pressure relief means, forming a concave portion, or forming a thin portion. be able to. In this case, it is preferable that one surface of the branch flow path wall is formed on the nozzle-side surface layer surface that is an interface with the external air layer, and the branch flow path wall is configured by a damper member having a small Young's modulus.

Further, when the damper member is constituted by one member common to a plurality of branch flow passages, the plurality of branch flow passages are inexpensive and have a simple structure and have a sufficient acoustic capacity and a sufficient acoustic stroke. It is possible to obtain an ink jet recording head having a configuration that can suppress it.

Here, when the damper member has an acoustic capacity of the branch flow path per ejector as c _p and an acoustic capacity of the nozzle as c _n , the following equation c _p > 10c _n. It is preferable to satisfy (1). Alternatively, instead of the, when said damper member, the acoustic capacitance of the branch channel of one per the ejectors c _p, the acoustic capacitance of the pressure chamber and c _c, the following equation _{c p>} 20c c ... It is also a preferable mode to satisfy (2). In these cases,
Since acoustic crosstalk can be suppressed and a sufficient amount of ink can be supplied from the branch flow path to each ejector at high speed, stable ejection of all ejectors can be performed simultaneously at a high frequency.

[0035] as "acoustic capacitance c _p of the branch flow path per ejector" in the present invention, the acoustic capacitance of one branch flow path divided by the number of ejectors disposed in communication with the said branch passages Means a value.

Conventionally, the acoustic capacity condition of the ink pool for suppressing the acoustic crosstalk in the linear array head and preventing the ink supply shortage is disclosed in Japanese Patent Laid-Open No. 56-758.
No. 63 and Japanese Patent Laid-Open No. 59-26269. JP-A-56-75863 (Prior Art A)
Discloses that it is possible to suppress the occurrence of crosstalk by setting the volume of the common ink channel to be at least twice the total volume of the pressure generating chamber (including the neighboring channel). In Japanese Patent Laid-Open No. 59-26269 (Prior Art B), the impedance Z _R of the common ink flow path is set to Z _R based on the number N of ejectors connected to the common ink flow path and the impedance Z _S of the ink supply path. ≦ Z _S / (10N)
There is disclosed an inkjet recording head that suppresses the occurrence of crosstalk by setting such that As described above, in the above disclosed examples (prior arts A and B), the capacity or impedance of the common ink flow path is set based on the capacity of the pressure generating chamber or the impedance of the ink supply path. From these experimental results, it was found that stable ink droplet ejection cannot be realized under these conditions.

On the other hand, as a result of performing many discharge observation experiments, fluid analysis, equivalent circuit analysis, etc., the inventors found that the amount of change in refill time with respect to the number of simultaneous discharge ejectors was
It is governed by the ratio of c _n and c _p, also found that the crosstalk is governed by the ratio of c _c and c _p. That is, in the ink jet recording head according to the present invention, by setting the value of c _p / c _n and c _p / c _c so as to satisfy the conditions shown by the formula (1) and (2), matrix Even in a head having a plurality of narrow branch channels such as an array head, it is possible to suppress acoustic crosstalk and prevent shortage of ink supply, and to realize stable continuous ejection from multiple ejectors at the same time. And The background of the invention will be described below.

First, the process of finding the conditions for preventing pressure wave interference between the ejectors, that is, acoustic crosstalk, will be described. As a result of performing a large number of head prototype evaluations and acoustic analysis using the equivalent circuit of the head shown in FIG. 13, the present inventors found that the incidence of acoustic crosstalk was substantially only the ratio of c _p and c _c. I have found that it depends. Here, symbols c, m, and r in FIG. 13 indicate acoustic capacitance, inertance, and acoustic resistance, respectively, and subscripts d, n, i, and p indicate a piezoelectric element, a nozzle, an inlet, and a branch flow path, respectively.
For example, the c _d, shows the acoustic capacitance of the piezoelectric element. In addition,
The wide main channel was analyzed as having sufficient acoustic capacity.

[0039] With reference to the equivalent circuit analysis of Figure 13, shows the result of incidence of the acoustic crosstalk was examined how the change due to a change in c _p / c _c in FIG. Here, the acoustic crosstalk occurrence rate is calculated from the droplet velocity v ₁ when one ejector is ejected independently and the droplet velocity v ₂ when all ejectors are ejected at the same time. v ₂ -v ₁₎ / v was defined as _1.

As shown in the graph of FIG. 14, the acoustic crosstalk incidence gradually increases with the increase of _{c p} / c c, c
_p / _c c increases rapidly from around beyond the 0.1, c _p
/ C _c to peak between 1-2. After that, c _p / c _c
With the increase of, acoustic cross-talk is reduced sharply, c _p
> Satisfies the condition of 20c _c, acoustic crosstalk incidence seen that can be kept below 7% to 8%.

[0041] More preferably, if c _p> 50c _c acoustic crosstalk than 5%, it is found that can each suppress acoustic crosstalk to 1% or less if _{c p>} 100c c. cause the value of c _p / c _c audio crosstalk significantly increased between 1-2, vibration occurs in the pressure wave in the ink in the branch passage by the pressure wave propagated from the pressure chamber, the branch flow It is considered that since the vibration frequencies of the pressure wave vibration generated in the passage and the pressure wave vibration in the pressure chamber are close to each other, both vibrations interfere with each other and a kind of resonance phenomenon occurs.

Strictly speaking, the inertance m _p of the branch flow path and the acoustic resistance r _p have an influence on the acoustic crosstalk occurrence rate, but the influence is extremely small in a normal ink jet recording head, and the acoustic crosstalk is substantially caused. We have found that the incidence is governed by c _p / c _c as described above. The absolute value of the rate of occurrence of acoustic crosstalk, nozzle shape, the inlet shape and the pressure chamber shape is different for each head shape, relative increase or decrease of the acoustic crosstalk incidence by the value of c _p / c _c described above It was confirmed that the relationship was constant regardless of the head shape, and was as shown in FIG.

Similarly, the present inventors have found that the ink refill time depends on the ratio of c _p and c _n by carrying out trial evaluation of a head and equivalent circuit analysis. Figure 1
5 shows the results of examining the relationship between c _p / c _n and refilling time t _r graphically. From the graph, c up to c _p / c _n = 1
Nearly it shows a constant refilling time regardless of the value of _p / c _n,
When c _p / c _n = 1 is exceeded, the refill time increases sharply,
After that, it can be seen that the peak is reached between c _p / c _n = 3-4. Thereafter, with the increase of c _p / c _n, refill time decreases rapidly, satisfy the conditions of c _p> 10c _n, revealed that it is possible to prevent a sharp increase in the refill time.

The reason why the refill time sharply increases and reaches a peak between c _p / c _n = 3 to 4 is that the pressure wave in the pressure chamber and the pressure wave in the branch channel are the same as in the case of the acoustic crosstalk. It is considered that there is interference between The absolute value of the refill time, the nozzle shape, the inlet shape and the pressure chamber shape is different for each head shape, relative relationships increase or decrease of the values and the refill time of c _p / c _n mentioned above is dependent on head geometry It was confirmed that the relationship was constant and the relationship shown in FIG. 15 was obtained.

Even if the refill time is increased, the inertance m _p and the acoustic resistance r _p of the branch flow channel are small, and in a normal ink jet recording head, the characteristic setting of the branch flow channel is performed based on c _p / c _n. It was clarified from the results of trial production of a plurality of types of inkjet recording heads that the above procedure should be performed.

As described above, in order to suppress the acoustic crosstalk and the ink supply shortage, the present inventors have c _p >.
It found that may satisfy the two conditions of 10c _n and _{c p>} 20c c. Also, note that if particular 0.1 <range of _{c p} / c c <10 or _{1 <c p / c n <} 10 is very large acoustic crosstalk occurs or refill time is sharply increased I found that Based on the above results, the inkjet recording head of the present invention has c _p > 10.
is characterized acoustic capacity of the ink pool to satisfy the two conditions that c _n and c _p> 20c _c in that the optimum setting, by satisfying this condition, a matrix having a narrow branching channel width Also in the array head, it is possible to suppress an increase in refill time and suppress acoustic crosstalk.

In the ink jet recording head according to the present invention, when the damper member is arranged on the nozzle surface layer side in the matrix array head, the damper member can be used also as the nozzle plate, and the nozzle is directly formed on the damper member. be able to. With this configuration, it is possible to reduce the number of parts and the manufacturing process, and to configure the pressure damper at low cost even in a matrix-shaped array head having a plurality of branch channels.

In the ink jet recording head according to the present invention, it is preferable that the damper member has a plate thickness of 20 μm or more and 100 μm or less. When forming the nozzle on the damper member, it is important to optimize the plate thickness of the damper member so that the pressure damper function and the nozzle function can both be achieved. By reducing the plate thickness of the damper member, it is possible to increase the acoustic capacity of the ink pool, but on the other hand, if the plate thickness is extremely reduced, there is a problem that bubbles are likely to be entrained from the nozzle surface during ink droplet ejection. It turned out to occur.

As a result of investigating the relationship between the nozzle length and bubble entrainment, the present inventors experimentally confirmed that the nozzle length is required to be 20 μm or more in order to prevent bubble entrainment. On the other hand, when the length of the nozzle becomes extremely long, the inertance of the nozzle increases, so that the ejection efficiency decreases and the refill time increases. In addition, a typical inkjet recording head has a nozzle diameter of 30 μm.
Although it is about m or less, there is a processing limit on the length of the nozzle in order to form such a fine nozzle on the nozzle plate with high accuracy. It was experimentally confirmed that the nozzle length must be at least 100 μm or less, preferably 75 μm or less in order to satisfy the above conditions.

In the conventional matrix-shaped array head, there is no description about specific means for providing the pressure damper to the branch flow passage. For example, Patent No. 28
In JP-A-06386, one surface of the ink supply groove (corresponding to a branch flow path) is composed of a nozzle plate, but there is no description about the pressure damper performance such as thickness and material of the nozzle plate. In Japanese Patent Application Laid-Open No. 9-156095, there is no description about the material or thickness of the ink common flow path (corresponding to the branch flow path), and the coating forming the ink common path (corresponding to the branch flow path). The bodies are independent of each other, and there is no description that they are composed of one common member as in the present invention. According to Japanese Patent Publication No. 10-508808, one surface of the ink supply duct is formed on the surface layer side of the nozzle, and the wall surface of the ink supply duct is composed of one orifice plate. It is made of a metal material, and no technique concerning the pressure damper performance such as the thickness of the orifice plate is disclosed.

In the ink jet recording head according to the present invention, it is preferable that the damper member is made of a film-shaped organic compound. Examples of the film-shaped organic compound include acrylic resin, aramid resin, polyimide resin, aromatic polyamide resin, polyester resin, polystyrene resin, nylon resin, and polyethylene resin. .

Generally, a metal material such as stainless steel, glass, ceramics, organic compounds or the like can be used as the head constituent member, but the elastic modulus (Young's modulus) is small in order to realize a sufficient pressure damper function. It is preferable to use an organic compound. Further, in the ink jet recording head of the present invention, it is necessary to form nozzles on the damper member, but it is possible to easily form highly accurate nozzles by excimer laser processing if it is a film-shaped organic compound. . Although the damper member can be made of a metal material or ceramic, a metal material or ceramic whose Young's modulus is one to two orders of magnitude higher than that of an organic compound for a matrix array head having a narrow branch flow path. When applying, it is necessary to form the damper member to be extremely thin.

In the present ink jet recording head which can be constructed so that the damper member is exposed on the nozzle surface layer side, an unexpected excessive stress may act on the damper member due to a paper jam or the like. For this reason, it is practically difficult to use an extremely thin metal material as the damper member. On the other hand, when the damper member is formed of a film-shaped organic compound, it is possible to increase the plate thickness several times as compared with the case of using a metal material,
It is possible to obtain an effect that damage does not occur even when external force such as paper jam occurs.

When the film-shaped organic compound is composed of a polyimide resin, the polyimide resin has a high heat resistance temperature.
Therefore, when a polyimide resin is used for the damper member, a thermal process such as 270 ° C. can be used in a post process of head assembly. Generally, various bonding steps are used for assembling the ink jet recording head. When a polyimide resin is used as the damper member, various thermosetting adhesives or thermoplastic adhesives can be used. For example, when a polystyrene resin is used as the damper member, an epoxy adhesive having a curing temperature of 200 ° C. cannot be used. In addition, the polyimide resin is a chemically stable material and has a characteristic of being excellent in chemical resistance to ink. Further, the polyimide resin has a feature that it can be processed by an excimer laser with extremely high precision nozzles without burrs. The term "polyimide resin" used herein means a polymer compound having an imide bond in the main chain.

In the preferable ink jet recording head of the present invention, the pressure generating means includes a piezoelectric element and a pressure plate for transmitting the displacement of the piezoelectric element to the ink in the pressure chamber, and the pressure generating means can perform ejection. The maximum drop amount is set to 15 pl (picoliter) or more. In this case, since a large ink droplet of 15 pl or more can be ejected,
Good image formation can be performed with a printing resolution of 300 dpi to 600 dpi, and a significantly high speed printing is possible as compared with the case of printing with a high resolution of 1200 dpi.
Further, it is preferable that the pressure generating means including the piezoelectric element and the pressure plate is configured by a piezoelectric actuator in which the pressure plate is flexibly deformed by expansion and contraction deformation of the piezoelectric element. In this case, the matrix array head can be easily realized.

In order to print good characters or images by the ink jet recording system, at least 300 dpi,
Preferably, a printing resolution of 600 dpi or higher is required. Since almost all inkjet recording type printers currently commercialized have a resolution of 300 dpi or more, it is understood that the above resolution is an essential condition for ensuring image quality (however, , Except for draft printing mode for high-speed printing).

When printing is performed at a printing resolution of 300 dpi using a commonly used water-based dye-based ink, in order to obtain a sufficient image density without white spots, a maximum of at least 15 pl, preferably 20 pl or more. The amount of discharged droplets is required. Similarly, in order to perform printing at a printing resolution of 600 dpi, even when using an ink whose composition is adjusted so that the dot diameter is widened within a range that does not significantly deteriorate the image quality on the recording paper, it is 10 pl or more, preferably 15 pl.
The above maximum ejected droplet amount is required. When the printing resolution is further increased, the required maximum drop amount is reduced, but in this case, there is a problem that the printing speed is lowered as shown below. For example, when printing is performed at a resolution of 1200 dpi, it is possible to form an image having a sufficient density with a maximum drop amount of about 4 to 5 pl. However, if the print resolution is improved, the amount of print data is increased. Therefore, if the number of nozzles is the same, there is a problem that the print speed is reduced as the resolution is increased. On the other hand, if the print resolution is reduced to realize high-speed printing, the problem of image quality deterioration occurs.

As a printing method which solves such conflicting problems and makes printing speed and image quality compatible, there is known a drop diameter modulation recording method in which the amount of ejected droplets is controlled. In the droplet size modulation recording method, a piezoelectric element is used as the pressure generating means, and by controlling the drive voltage waveform applied to the piezoelectric element, a small droplet with a small droplet amount to a large droplet with a large droplet amount can be ejected from the same nozzle. Has features. Combined with such drop size modulation technology, 300dpi to 60dpi
With a print resolution of 0 dpi, it is possible to realize image quality equivalent to high resolution recording of 1200 dpi. However, even if the droplet size modulation technique is used, the printing resolution is dominant in the character quality, and at least 300 dp
A printing resolution of i, preferably 600 dpi is required.

The present ink jet recording head realizes both the printing speed and the image quality as described above. Further, in order to realize a good image and high-speed printing with a resolution of 300 dpi to 600 dpi by applying the droplet diameter modulation technique, a piezoelectric element as a pressure generating means and a pressurization for transmitting displacement of the piezoelectric element to ink in the pressure chamber. It is configured to include a plate and capable of ejecting a droplet amount of 15 pl or more. With this inkjet recording head,
The pressure damper is configured so that ink droplets can be continuously and stably ejected at a high ejection frequency even when ejecting a large droplet of 15 pl.

The pressure generating means using a piezoelectric element is a single-plate piezoelectric actuator that utilizes the flexural deformation of an actuator composed of a piezoelectric element and a pressure plate as an output, and a plurality of piezoelectric element layers are laminated to expand and contract the piezoelectric element. It is roughly classified into a laminated actuator that utilizes deformation as an output. With a matrix-shaped array head in which ejectors are arranged two-dimensionally,
It is difficult to use the laminated actuator from the viewpoint of mounting technology and manufacturing cost, and it is preferable to use an inexpensive single plate piezoelectric actuator as the pressure generating means.

In the present specification, the liquid ejected from the nozzle is generically called "ink". Therefore, as the ink ejected from the nozzles of the inkjet recording head according to the present invention, a printing ink, a liquid containing an organic EL element material, or a liquid containing an organic semiconductor material can be used. When the printing ink is used, the inkjet recording head can be applied to an inkjet recording device that can obtain a good image. In addition, organic EL
When the liquid containing the element material is used, the ink jet recording head can be applied to an organic EL display manufacturing element, an organic EL display manufacturing head, and an organic EL display manufacturing apparatus in which an organic EL display substrate is applied. it can. Furthermore, in the case of using a liquid containing a material for an organic semiconductor, an inkjet recording head is used for an organic semiconductor element manufacturing element, an organic semiconductor element manufacturing head, and an organic semiconductor element manufacturing apparatus in which an organic semiconductor element substrate is applied. Can be applied.

[0062]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail based on the embodiments of the present invention with reference to the drawings. First Embodiment Example FIG. 1 is a plan view showing the configuration of an ink jet recording head (hereinafter, also simply referred to as a recording head) according to the first embodiment of the present invention, and FIG. 2 is taken along line AA of FIG. FIG.

As shown in FIG. 1, the ink jet recording head (ink jet ejection element) 20 of this embodiment.
Is an ink pool 17 to which ink is supplied from an external ink tank (not shown) through an ink supply port 19.
And a plurality of ejectors arranged in a matrix. The ink pool 17 includes one linear main flow path 16
And the straight branch channels 15 that are parallel to each other and branch from the main channel 16 in a direction substantially orthogonal to each other. As shown in FIG. 2, each ejector includes a pressure chamber 12 that communicates with a branch flow path 15 via an inlet 14, and a pressure plate 21 and a single-plate-shaped piezoelectric element 22 arranged on the bottom surface of the pressure chamber 12. And a nozzle 11.

When a drive voltage waveform is applied to the piezoelectric element 22 from a drive circuit (not shown), the pressure plate 21 is flexibly deformed by the expansion and contraction of the piezoelectric element 22, and the volume of the pressure chamber 12 can be expanded and expanded. it can. Due to the abrupt volume change of the pressure chamber 12, a pressure wave is generated in the ink inside the pressure chamber 12 and an ink droplet is ejected from the nozzle 11. Here, a stainless rolled thin plate was used as the pressure plate 21, and the pressure plate 21 was used as a common electrode for supplying a drive voltage waveform to the piezoelectric element 22. As shown in FIG.
The drive voltage waveform applied to each piezoelectric element 22 is supplied from the flexible wiring board 24 arranged below the piezoelectric element 22 via the bump 23.

One surface of the branch flow path 15 is composed of a damper member 18 arranged on the surface layer side of the nozzle 11. The damper member 18 is formed with a plurality of nozzles 11 arranged in a matrix. An ink repellent material that repels ink is applied around the nozzle 11 on the damper member 18. The damper member 18 has a Young's modulus of 8G.
Nozzle 11 made of polyimide resin film of Pa
Are formed by excimer laser processing to have an opening diameter of 30 μm.

The damper member 18 is composed of one common damper member 18 for the plurality of branch flow paths 15.
By covering a plurality of branch flow paths 15 with one damper member 18, a pressure damper mechanism is collectively formed on each branch flow path 15. In the present embodiment example, one surface of the main flow path 16 is also formed on the surface of the nozzle 11 side similar to the branch flow path 15, and the damper member 18 provided on the branch flow path 15 is provided.
Thus, the surface layer surface of the main channel 16 on the nozzle 11 side is formed. With such a configuration, the mainstream 16
Also, it is possible to provide a sufficient acoustic capacity that does not cause the ink supply shortage.

As shown in FIG. 1, this recording head is provided with nine ejectors communicating with one branch flow path 15, and the pitch between the ejectors in the sub-scanning direction is 300 lines / inch.apprxeq.84.7 .mu.m. The ejectors are arranged so that Further, the number of branch flow paths 15 is eight, and the total is seven.
Inkjet ejection element 20 of one color with two ejectors
Is configured.

This recording head was manufactured as follows. As shown in FIG. 2, from the main flow channel 16 (FIG. 1) to the branch flow channel 1
5, the nozzle 11 via the inlet 14 and the pressure chamber 12
The ink flow path up to is composed of three plates, an ejector plate 25, a damper member 18, and a pressure plate 21.

In the ejector plate 25, a plurality of pressure chambers 12 arranged in a matrix, a plurality of branch flow passages 15 having a straight inverted triangular cross section, and the branch flow passages 15 and the pressure chambers 12 are provided. An inlet 14 that communicates with each other is formed. Using a Si substrate as the ejector plate 25, a general semiconductor process such as exposure and development and film formation, and an anisotropic wet etching process utilizing the (100) plane of Si are used to form a square pyramidal pressure chamber 1.
2, the inlet 14 and the branch channel 15 are integrally formed on the ejector plate 25. Inlet 14 has a width of 68
It has an inverted triangular cross section with a height of 48 μm and a length of 100 μm.

Next, after the damper member 18 made of a polyimide resin film is fixed to the ejector plate 25 with a thermoplastic adhesive, it is processed by excimer laser processing.
The nozzle 11 was formed at a position corresponding to each pressure chamber 12 in the damper member 18. Furthermore, the nozzle 11 of the pressure chamber 12
A pressure plate 21 made of stainless steel is fixed to the surface on the opposite side of the pressure plate with a thermoplastic adhesive, and the pressure chamber 1 of the pressure plate 21 is
The piezoelectric element 22 was fixed to the position corresponding to 2 by adhesion. Electrodes (not shown) were previously formed on both surfaces of the piezoelectric element 22 by a sputtering method. Finally, the flexible wiring board 24 and the piezoelectric element 22 were connected via the solder bumps 23, and the manufacturing process of the recording head was completed.

FIG. 3 is a plan view showing the ink jet recording head of this embodiment. The inkjet recording head 26 integrally includes four inkjet ejection elements 20a to 20d arranged in a line in the main scanning direction. Each of the inkjet ejection elements 20a to 20d is 1
The book includes a main flow path 16, a plurality of branch flow paths 15, and a plurality of ejectors arranged in a matrix. The ink jet ejection element 20a is filled with black ink,
The inkjet ejection element 20b is filled with magenta ink, the inkjet ejection element 20c is filled with cyan ink, and the inkjet ejection element 20d is filled with yellow ink.

Next, the nozzle 11 in the present embodiment,
The relationship between the acoustic capacities of the pressure chamber 12 and the branch channel 15 will be described. In FIG. 2, for example, the width W _{d of the} branch channel 15
Is set to 637 μm, and the damper member 18 has a plate thickness of 20 μm.
A polyimide resin film having a Young's modulus of 8 GPa at m can be used. Each nozzle 11 on the damper member 18 can be formed to have a diameter of 30 μm by excimer laser processing, and the ink has a viscosity of 3 mPa · s.
A water-based ink having a surface tension of 35 mN / m can be used.

Acoustic capacity c of pressure chamber 12_cIs given by
Be done. Where W_cIs the pressure chamber volume [m ³], Κ is the ink
The bulk modulus [Pa] and K depend on the rigidity of the pressure chamber, etc.
It is a positive coefficient.

[0074]

[Formula 3]

The pressure chamber 12 in the present embodiment has, for example, a quadrangular pyramid shape with a bottom surface of 500 μm square and a height of 350 μm, and its volume is 2.9 × 10 ^-11 m ³ . Bulk modulus of the water-based ink is 2.2 × 10 ⁹ Pa, because the correction coefficient K is 0.3 result obtained by experiment evaluation, c _c is ^{4.4 × 10 -20 [m 5 /} N] Met.

The acoustic capacity c _n of the nozzle is expressed by parabolic approximation of the meniscus shape with the nozzle opening diameter d _n [m], the ink surface tension σ [N / m], and the meniscus drawing amount y [m]. It can be expressed as:

[0077]

[Formula 4]

As shown in equation (4), the acoustic capacity of the nozzle c _n
Depends on the meniscus pull-in amount y, but in the present embodiment, the value of c _n was estimated by the following equation by defining y = d _n / 4.

[0079]

[Formula 5]

In this embodiment, the nozzle diameter is 30 μm,
Since the surface tension of the ink is 35 mN / m, c _n is 1.5 × 10 ⁻¹⁸ [m ⁵ / N].

In the present embodiment, the surface layer of the branch passage 15 on the nozzle 11 side is constituted by the damper member 18, and a pressure damper is provided. The pressure damper of the present embodiment, since the beam structure at both ends support, acoustic capacity c _d a pressure damper which is constructed on the branch flow path 15 can be approximated by the following equation. Here, w _d is a branch flow channel width [m], t _d is a damper member thickness [m], l _d is a branch flow channel length per ejector [m], and E _d is a damper member. Elastic modulus (Young's modulus) [Pa] and ν _{d respectively} represent the Poisson's ratio of the damper member.

[0082]

[Formula 6]

In the recording head of the present embodiment, as described above, the width W _d of the branch flow passage 15 is set to 637 μm and the distance l _d between the ejectors is set to 700 μm. A polyimide film having an elastic modulus of 8 GPa, a Poisson's ratio of 0.4 and a thickness of 20 μm was used as the damper member 18. Therefore, the acoustic capacitance c _d of the pressure damper per ejector is a ^{_{c d = 1.6 × 10 -17 [}} m 5 / N]. In the present recording head, since the acoustic capacity of the ink itself filled in the branch flow path 15 is extremely small, it can be considered that the acoustic capacity of the branch flow path 15 is substantially equal to the acoustic capacity of the pressure damper. Thus, the acoustic capacitance c _p of the branch flow path 15 is a ^{_{c p = 1.6 × 10 -17 [}} m 5 / N].

As is clear from the calculation results of the respective parameters as described above, in the recording head of this embodiment, the branch channel 1
Acoustic capacitance c _p of 5 10.7 times the acoustic capacitance c _n of the nozzle,
And, acoustic capacity c _p of the branch flow path 15 is about 363 times the acoustic capacitance c _c of the pressure chamber 12, which satisfies both the condition of Equation (1) and (2).

Using the recording head of this embodiment, ink droplets of 15 pl were ejected while changing the number of simultaneous ejection ejectors, and the refill time was examined. The results are shown in the graph of FIG. In this graph, the difference in refill time between single discharge and simultaneous discharge of all ejectors is ± 1 μs.
It can be seen that it almost matches the following. The average refill time when all ejectors are simultaneously ejected (marked with ◆) is 4
The average refill time was 7.5 μs and the average refill time was 45.9 μs in the case of individual discharge (marked with “◯”), and the difference in refill time between the ejectors matched with a deviation of ± 0.4 μs or less.

In the recording head of this embodiment, the diameter of the ink droplet ejected from the nozzle 11 can be easily changed by adjusting the drive voltage waveform applied to the piezoelectric element 22. Therefore, the drive voltage waveform applied to the piezoelectric element 22 was adjusted, and the refill time when 20 pl of ink droplets were ejected was examined. That is, when ejecting 20 pl of ink droplets, the refill time is slightly longer because the droplet volume is larger than when ejecting 15 pl of ink droplets, but it is different from the case of single ejection and when all ejectors are ejected simultaneously. Then, it was confirmed that the refill times agree with each other within a deviation of ± 2.0 μs. The average refill time of all ejectors during single ejection was 57.0 μs, and the average refill time of all ejectors during simultaneous ejection of all ejectors was 60.4 μs. It was also confirmed that 20 pl of ink droplets can be ejected simultaneously by all ejectors simultaneously and stably at an ejection frequency of 15 kHz.

From the above measurement result of the refill time, it was confirmed that the pressure damper mechanism constituted by the damper member 18 worked sufficiently to suppress the ink supply shortage.
The measurement of the refill time was performed by magnifying and observing the meniscus state of the nozzle surface while synchronizing with a strobe, and measuring the time until the meniscus surface returned to the initial state. The measurement accuracy of the refill time was about ± 1 μs. The ejector numbers on the horizontal axis in FIG. 4 are the ejector at the upper left end in FIG. 1, the ejectors next to each other are numbered 2 and 3, and the ejector at the lower right end is 72.
It's my turn.

As described above, by constructing the damper member 18 with a polyimide film having a thickness of 20 μm and a Young's modulus of 8 GPa even for a narrow branch channel, it is possible to provide a sufficient acoustic capacity to the branch channel 15. confirmed.
Therefore, continuous ejection was performed while driving all ejectors, and it was examined whether stable ejection was possible at a high frequency of 20 kHz. As a result, it was confirmed that even when a 15 pl ink droplet was simultaneously ejected from all the ejectors at a frequency of 20 kHz, it was possible to realize stable ejection equivalent to that in single ejection. In addition, as a result of measuring the drop velocity in order to investigate the influence of acoustic crosstalk, it was confirmed that the difference in drop velocity between the single ejection and the simultaneous ejection of all ejectors was within ± 2%. From the above, it was confirmed that the acoustic crosstalk between the ejectors was also successfully suppressed.

As a comparative object, the same evaluation was performed for a case where a stainless steel plate (E _d = 197 GPa, ν = 0.3) was used for the damper member 18. First, according to equation (6),
Obtained relation between the acoustic capacity c _p of the thickness of the branch flow path 15 of the damper member 18, or plates c _p / c _n and c _p / c _c by the thickness of the damper member 18 is how to change the theoretical formula I asked. The result is shown in FIG. From the graph of FIG. 5, when a stainless steel plate is used for the damper member 18, the plate thickness of the damper member 18 is set to 7 μm in order to satisfy the equation (1) for suppressing shortage of ink supply and realizing high-speed ink refill.
It has been found that it needs to be reduced to Further, it has been found that the plate thickness of the damper member 18 must be 19 μm or less in order to satisfy the expression (2) for suppressing the acoustic crosstalk. In order to verify the above analysis results, the plate thickness of the stainless steel damper member 18 was variously changed, and the same evaluation as in the case of using the above polyimide damper member was performed.

Comparative Example 1 In this comparative example, the thickness of the damper member 18 made of stainless steel was set to 1
It was set to 0 μm. In the ink jet recording head of the present comparative ^{_{example, c p = 5.2 × 10 -18}} [m 5 / N] is (c _p / c _n = 3.5 and _{c p / c c = 137)} , the formula (2 ) Is satisfied, but formula (1) is not satisfied.

FIG. 6 shows the results of examining the ink refill time when ejecting 15 pl ink droplets. From the graph, it can be seen that when simultaneous ejection is performed from all the ejectors, the ink supply becomes insufficient, and the refill time is significantly increased as compared with the case of single drive. As a result of performing the ejection evaluation at the ejection frequency of 20 kHz, it was confirmed that stable ejection was possible by single drive, but when all ejectors were ejected simultaneously, a large number of ejectors became unstable in ejection state. . In the case of the single drive, one ejector can occupy one branch flow path 15, so that the acoustic capacity of the branch flow path 15 per ejector increases several times as compared with the simultaneous ejection of all ejectors. For this reason, it is 20 kHz when driven independently.
It is considered that stable discharge was achieved with.

The above acoustic capacity c _p = 5.2 × 10 ^-18 [m
⁵ / N] indicates the value when all ejectors are simultaneously ejected. However, it was found that the acoustic capacity of the branch flow channel 15 was insufficient during simultaneous ejection of all ejectors, and the following refill time difference occurred between a plurality of ejectors communicating with one branch flow channel 15. As can be seen from the graph of FIG. 6, in the ejector close to the main flow path, the refill time was about 47 μs, which was the refill time at which ejection was possible at 20 kHz. On the other hand, in the ejector at the end far from the main flow path, the refill time was 60 μs or more, which was 13 μs or more longer than that in the ejector near the main flow path.

For this reason, the ejector at the end far from the main flow path became unstable in the ejection state at the ejection frequency of 20 kHz, and some ejectors also failed to eject. With simultaneous ejection of all ejectors, the ejection frequency is 13 to 15 kHz.
Stable discharge became possible by reducing to about z. It is considered that the acoustic capacity of the branch flow path 15 increases at least several times when driving all the ejectors when driven alone. These results are almost in agreement with the analysis results shown in FIG. 15, and the effectiveness of the present invention could be confirmed experimentally.

The present inkjet recording head, which was experimentally evaluated as a comparison target, satisfies the conditions of the prior art A and the prior art B. That is, by setting the common ink channel characteristics based on the prior art, it is impossible to achieve a stable high frequency discharge, the acoustic capacitance c _p of the common ink flow path in response to the acoustic capacitance c _n of the nozzle It was confirmed for the first time that stable and continuous ejection of all nozzles could be realized by optimally setting. As for the droplet speed, similar to the first embodiment of the present invention, since the deviations within ± 2% during single ejection and simultaneous ejection of all ejectors match, acoustic crosstalk between ejectors is also good. It was confirmed that it was suppressed to.

Comparative Example 2 In this comparative example, the same ejection evaluation was performed with the damper member 18 having a plate thickness of 15 μm. In the recording head of this comparative example, c _p = 1.6 × 10 ⁻¹⁸ [m ⁵ / N]
c _p is 1.1 times c _n and 42 times c _c.
Similarly, it was confirmed that acoustic crosstalk did not occur. On the other hand, in the case of driving at the ejection frequency of 20 kHz, the ejection state became unstable even when driven alone. The ejection frequency that enables stable ejection was 13 to 15 kHz. It was confirmed that this result also matches the analysis result shown in FIG.

Comparative Example 3 In this comparative example, the same ejection evaluation was performed with the damper member 18 having a plate thickness of 20 μm. As referred to in the recording head of the present comparative ^{_{example, c p = 6.5 × 10 -19}} [m 5 / N],
c _p is about 0.4 times c _n and 17 times c _c . In this comparative example, the influence of acoustic crosstalk appears, and the droplet speed is 7 to 7 when all ejectors are simultaneously ejected as compared with the case of single drive.
8% reduction. This result almost agrees with the analysis result shown in FIG. On the other hand, the frequency at which the ejection is stable during simultaneous ejection of all ejectors was 13 to 15 kHz or less. This result also agrees with the analysis result of FIG. 15, confirming the effectiveness of the present invention.

Comparative Example 4 In this comparative example, the same ejection evaluation as above was carried out with the damper member 18 having a plate thickness of 30 μm. In the recording head of this comparative example, c _p is about 0.13 times c _n and 5 times c _c such that c _p = 1.9 × 10 ⁻¹⁹ [m ⁵ / N]. In this comparative example, the influence of the acoustic crosstalk is remarkable, and the droplet speed when all ejectors are simultaneously ejected is reduced by 15 to 20% as compared with the case of single drive, the droplet speed is not stable, and the ejection state becomes extremely unstable. became. It was confirmed that this result also agrees with the analysis result shown in FIG. In this comparative example, since acoustic crosstalk remarkably occurs, a stable ejection frequency could not be obtained.

From the above Comparative Examples 1 to 4, it is possible to realize a high-speed ink refill by suppressing the ink supply shortage if the relationship of the expression (1) is satisfied, and if the expression (2) is satisfied, the acoustic crosstalk is achieved. It was confirmed that each of the above can be suppressed. Further, in the case of a matrix-shaped array head in which the width of the branch flow path 15 is narrow, when a metal material such as stainless steel is used for the damper member 18, a large ink droplet of 15 pl is generated.
It was confirmed that in order to continuously and stably eject at a high ejection frequency such as kHz, the damper member 18 needs to be configured to have an extremely thin thickness such as 7 μm.

The stainless steel material having a plate thickness of 7 μm substantially has a large number of pinholes, and is difficult to handle at the time of manufacturing due to its strength. Even if it is possible to manufacture a head with a stainless steel material having a thickness of 7 μm, the damper member 18 is damaged when an external force directly acts on the pressure damper portion due to a paper jam or the like, and thus the substantially matrix shape is formed. It was confirmed that it was extremely difficult to apply to the array head.

As described above, in order to realize stable ejection at a high ejection frequency and to achieve a high-density array of ejectors with a matrix-shaped array head having a narrow width of the branch flow path 18, a polyimide resin or the like is used. It was confirmed that the use of a film-like organic compound having a Young's modulus one to two orders of magnitude smaller than that of a metal material is essentially an essential condition. Further, it was confirmed that a pressure damper mechanism having sufficient ability can be formed in all the branch flow passages 15 by forming the wall surface on the nozzle 11 side of the plurality of branch flow passages 15 with one film damper member 18. did it.

Second Embodiment Example FIG. 7 is a plan view showing an ink jet recording head of this embodiment example, and FIG. 8 is a sectional view taken along the line BB of FIG.

As shown in FIG. 7, the recording head of this embodiment has an ink pool 17 in which ink is supplied from an external ink tank (not shown) through an ink supply port 19.
And a plurality of ejectors arranged in a matrix. In the present embodiment example, unlike the first embodiment,
The main flow path 16 extends linearly in the main scanning direction during printing, and the linear branch flow path 15 branched from the main flow path 16 in a direction substantially orthogonal to the main flow path 16 extends in the sub-scanning direction.

As shown in FIG. 8, each ejector has a pressure chamber 12 communicating with a branch flow passage 15 via an inlet 14.
And a pressure generating means 1 composed of a pressure plate 21 and a single-plate piezoelectric element 22 arranged on the bottom surface of the pressure chamber 12.
3 and a nozzle 11 communicating with the pressure chamber 12. As shown in FIG. 7, the pressure chamber 12 and the branch channel 15 are arranged so as to overlap each other when viewed from the nozzle 11 side.

In the recording head of the present embodiment as described above, ink droplets are ejected from the nozzle 11 by applying a drive voltage waveform to the piezoelectric element 22 by a circuit (not shown) as in the first embodiment.

One surface of the branch flow path 15 is composed of a damper member 18 arranged on the surface layer side of the nozzle 11, and the nozzle 11 is formed in this damper member 18. The damper member 18 forms a pressure damper mechanism on each of the branch flow paths 15 by covering all of the plurality of branch flow paths 15 with one elastic member common to all ejectors. In this embodiment, one surface of the main flow path 16 is also formed on the surface layer surface on the nozzle 11 side similarly to the branch flow path 15, and the main flow path 16 is provided by the damper member 18 provided on the branch flow path 15. A pressure damper for the main flow path 16 is also formed on the nozzle surface layer side.

In the present embodiment, as shown in FIG. 7, there are 15 ejectors communicating with one branch flow passage 15, and the pitch between ejectors in the sub-scanning direction is 300 / inch. Each ejector is arranged. In addition, the number of the branched flow paths 15 is 10, and 150 ejectors configure the inkjet discharge element 20 of one color.

The width d of the branch channel is 700 μm, and the plate thickness of the damper member 18 is 12.5 μm, 18 μm, and 20 μm, respectively.
Seven types of inkjet recording heads having a size of μm, 25 μm, 45 μm, 75 μm, and 100 μm were manufactured in total. A polyimide resin film having a Young's modulus of 5 GPa was used for the damper member. Nozzle 11 is excimer laser processed,
The opening diameter was 26 μm. As ink, the viscosity is 3.5
A water-based ink having mPa · s and a surface tension of 32 mN / m was used.

This recording head was manufactured as follows. As shown in FIG. 8, first, the pool plate 27,
Patterns corresponding to the branch passages 15, the inlets 14, and the pressure chambers 12 were formed on the inlate plate 28 and the pressure chamber plate 29 by wet etching, respectively.

Next, the pool plate 2 made of stainless steel
A total of three positions of 7, the inlet plate 28 and the pressure chamber plate 29 were aligned and joined using a thermoplastic adhesive. Subsequently, the damper member 18 made of a polyimide resin film having the surface coated with the ink repellent treatment agent was adhered to the pool plate 27. Further, by excimer laser processing, the damper member 1 is pressed from the pressure chamber plate 29 side.
Nozzle 11 was formed on No. 8. Subsequently, the pressure plate 21 was adhered to the pressure chamber plate 29 side. Then, the individualized piezoelectric element 22 was fixed directly under each pressure chamber 12 using a thermosetting adhesive. Subsequently, the flexible wiring substrate 24 was joined to each piezoelectric element 22 via the bump 23, and the present recording head was completed.

As shown in FIG. 8, the pool plate 27,
The pattern of holes and grooves formed by etching in the inlet plate 28 and the pressure chamber plate 29 is such that four inkjet ejection elements 20a to 20d as shown in FIG. 3 are arranged in the main scanning direction. A recording head in which four colors are integrated is manufactured by the manufacturing method of 1.

Here, Table 1 shows the acoustic capacities of the nozzle 11, the pressure chamber 12, and the branch channel 15 in the second embodiment.
Shown in.

[0112]

[Table 1]

From Table 1, the thickness of the damper member 18 is 25 μm.
If m or less, the condition of equation (1) and (2), that is, it can be seen that satisfies c _p> 10c _n and c _p> 20c _c at the same time. Regarding the suppression of acoustic crosstalk, if the plate thickness of the damper member 18 is 45 μm or less,
It can be seen that the condition of Expression (2) is satisfied.

The above-mentioned damper member 18 has a different plate thickness 7
FIG. 9 is a graph showing the results of examining the refill time for various types of recording heads. This graph shows one branch channel 1
5 shows refill times for 15 ejectors communicating with 5. As shown in the graph, when the plate thickness of the damper member 18 is 25 μm or less, the acoustic capacity of the branch flow passage 15 is sufficient, and therefore the refill time was about 45 μs in any head.

For the recording head in which the plate thickness of the damper member 18 is 25 μm, the refill time is shown for the case of single ejection and the case of simultaneous ejection of all ejectors. The refill times are almost the same when all ejectors are simultaneously ejected (marked by ◆) and when they are individually ejected (marked by ○), and the refill time difference between ejectors in one branch flow path is good. It was confirmed that it was suppressed to.

On the other hand, when the thickness of the damper member 18 is 45 μm or more, when all ejectors are simultaneously ejected,
It was confirmed that the increfill time increased sharply.
When the plate thickness of the damper member is 45 μm, 75 m and 100 μm, the average refill time is 90 μs, 81 μs and 7 μm, respectively.
It was 9 μs. The reason for the longest refill time when the damper member has a plate thickness of 45 μm is that c _p / c _n = 3.2 as shown in FIG. It is thought that this is due to the interference with the pressure wave of. It is understood that the ejector in the vicinity of the main flow path 16 and the ejector at the end of the branch flow path 15 communicate with the same branch flow path, but a refill time difference of 50 to 70 μs occurs.

Using the recording head in which the plate thickness of the damper member 18 is changed to seven types, 20 pl of ink droplets of 15 pl are used.
All ejectors were simultaneously ejected at a frequency of kHz. As a result, in the head in which the plate thickness of the damper member 18 is 45 μm or more, the ink supply becomes insufficient and the ejection becomes unstable,
Many nozzles failed to eject. In particular, the damper member 18
In the head having a plate thickness of 75 μm or more, the effect of acoustic crosstalk also appeared, and the droplet speed when all ejectors were simultaneously ejected decreased as compared with the case of single drive. Thickness 7 of damper member 18
With a 5 μm head, the drop velocity was reduced by about 10%, and the plate thickness was 1
With a head of 00 μm, the drop speed decreased by about 20%.

Further, since the inertance of the nozzle increases as the plate thickness of the damper member increases, the ejection efficiency decreases and the piezoelectric element 22 is required to eject an ink droplet of 15 pl.
The voltage applied to is increased. The voltage applied to the piezoelectric element 22 for ejecting a 15 pl droplet is
When the plate thickness was 75 μm, it was required to be about twice as large as that for the plate thickness of 25 μm, and for the plate thickness of 100 μm, about 2.5 times as much as that for the plate thickness of 25 μm. It was confirmed that the thickness of the damper member is limited to 100 μm from the viewpoint of discharge efficiency, preferably 75 μm or less, and more preferably 45 μm or less.

On the other hand, in the head in which the plate thickness of the damper member 18 is 25 μm or less, since the expressions (1) and (2) are satisfied at the same time, it is expected that the ink droplet of 15 pl can be stably ejected at the ejection frequency of 20 kHz. . However, in the head in which the plate thickness of the damper member 18 was 18 μm or less, nozzles that failed to eject occurred due to continuous ejection. Particularly, in a head in which the damper member 18 has a thin plate thickness of 12.5 μm, non-ejection nozzles remarkably occurred when performing continuous ejection. As a result of investigating the cause of non-ejection, it was confirmed that air bubbles were entrapped just below the nozzle 11. Here, it has been confirmed that the nozzles that have failed to eject can be ejected again by performing the ink suction operation that is normally performed in the inkjet recording head.

As described above, when the nozzle 11 is formed in the damper member, if the damper member 18 is extremely thin in order to satisfy the formulas (1) and (2), ink droplet ejection is performed. It became clear that air bubbles were trapped inside.
Therefore, the thickness of the damper member 18 should be at least 20 μm.
It was confirmed that it is necessary to form the film having a thickness of m or more.

Third Embodiment In this embodiment, the state of the recording head viewed from above is the same as FIG. 7 of the second embodiment, and therefore a description will be given with reference to FIG. 7 in common as a plan view. FIG. 10 is a sectional view taken along the line BB of FIG. 7 in the present embodiment example. The recording head of the present embodiment is the same as the second embodiment except that the nozzle plate 30 is arranged in addition to the damper member 18.

As shown in FIG. 10, one surface of the branch flow path 15 is constituted by a damper member 18 arranged on the surface layer side of the nozzle 11. Above the damper member 18, there is provided a nozzle plate in which a position corresponding to the branch flow path 15 is cut out. The plurality of branch flow paths 15 are collectively covered by a single damper member 18 made of an elastic member, whereby a pressure damper mechanism is formed on each branch flow path 15. In this embodiment, one surface of the main flow path 16 is also formed on the surface layer surface on the nozzle 11 side like the branch flow path 15, and the damper member 18 provided on the branch flow path 15 forms the nozzle surface layer surface of the main flow path 16. A pressure damper mechanism for the main flow path 16 is also formed on the side.

In this embodiment, the width W _d of the branch flow passage is 7
The thickness of the damper member 18 is 00 μm and the thickness of the damper member 18 is 25 μm. A polyimide resin film having a Young's modulus of 5.7 GPa was used for the damper member. The nozzle 11 was formed with an opening diameter of 26 μm by excimer laser processing. A water-based ink having a viscosity of 3.5 mPa · s and a surface tension of 32 mN / m was used as the ink.

The acoustic capacities of the nozzle 11, the pressure chamber 12 and the branch channel 15 in this embodiment are 9.9 × 1 respectively.
0 ^-19 [m ⁵ / N], 5.5 × 10 ^-20 [m ⁵ / N], 1.
It is 9 × 10 ⁻¹⁷ [m ⁵ / N]. c _p / c _n = 18.7,
Since c _p / c _c = 336, it can be understood that the conditions of Expression (1) and Expression (2) are simultaneously satisfied in the present embodiment example.

Using the recording head of this embodiment, the refill time was examined while changing the number of simultaneous ejection ejectors. As a result, similar to the recording head of the second embodiment, the case where all ejectors were simultaneously ejected was used. It was confirmed that the refill time was almost the same as when ejected, and the refill time difference between each ejector was well suppressed. Also,
It was confirmed that 15 pl of ink droplets could be stably ejected simultaneously with all ejectors at an ejection frequency of 20 kHz. An ink repellent material was provided near the nozzle 11 to prevent ink adhesion.

Fourth Embodiment In this embodiment as well, the state of the recording head viewed from above is the same as in FIG. 7 of the second embodiment, and therefore description will be given with reference to the plan view of FIG. 7 in common. FIG. 11 is a sectional view taken along the line BB of FIG. 7 in the present embodiment example. The recording head of the present embodiment differs from the second and third embodiments in that the pressure damper mechanism is formed inside the recording head.

As shown in FIG. 11, in the recording head of this embodiment, the ink path from the ink pool to the nozzle 11 has a nozzle plate 30 on which the nozzle 11 is formed.
And a pool plate 27 in which the branch channel 15 is formed,
The damper member 18, the inlet plate 28 having the recess 31 formed therein, the pressure chamber plate 29, and the pressure plate 2
It is obtained by laminating 1 and 1 in this order and adhering them to each other. The nozzle 11 is formed by excimer laser processing so as to have an opening diameter of 30 μm. Branch channel 15
Has a width of 700 μm and was formed by etching on a stainless steel thin plate.

The damper member 18 was formed with a hole forming a part of the inlet 14 by excimer laser processing. The damper member has a Young's modulus of 5.7 GPa and a thickness of 2
It is composed of a 5 μm polyimide resin film. On the inlet plate 28, a recess 31 for forming an air damper in combination with the damper member 18 is formed by half etching together with the round hole of the inlet 14. Here, the damper member 18 is composed of a single common member, whereby a pressure damper mechanism is collectively formed for the plurality of branch flow paths 15. In addition, the piezoelectric element 22, the flexible wiring board 24, and the bump 23
The configuration of is the same as that of the second and third embodiments.

In the recording head of this embodiment, the nozzle 1
1, the acoustic capacity of the pressure chamber 12 and the acoustic capacity of the branch channel are respectively 1.
^{8 × 10 -18 [m 5 /N],5.5×10} -20 [m 5 /
N] and 1.9 * 10 < ^-17 > [m < ⁵ > / N]. That is, c
_p / c _n = 10.5, c _p / c _c = 336, and the formula (1)
And satisfying the condition (2).

Using the recording head of this embodiment, the second
As a result of investigating the refill time while changing the number of simultaneous ejection ejectors as in the example of the embodiment, the refill times when single ejection and when all ejectors are simultaneously ejected are almost the same, and there is a deviation of ± 1 μs. It was In addition, almost no acoustic crosstalk occurred, and the acoustic crosstalk occurrence rate at the time of simultaneous driving of all ejectors was 1% or less.

As described above, even when the pressure damper mechanism is formed inside the head, by satisfying the expressions (1) and (2), the acoustic crosstalk can be prevented and the shortage of the ink supply can be suppressed. We were able to confirm that high-speed refill could be achieved.

Fifth Embodiment FIG. 12 is a conceptual diagram showing a main part of an ink jet printer (ink ejection device) equipped with an ink jet recording head according to the present invention. The ink jet printer 44 includes a control unit 3 including a microcomputer and the like.
5, a pressure driving unit 39, a head driving unit 34, and a sheet feeding unit 33 that conveys the recording sheet 32 while contacting the recording sheet 32. The inkjet recording head 26 has inkjet ejection elements 20A to 20D arranged in sequence along the main scanning direction indicated by arrow A.
The recording paper 32 is brought into contact with the paper feeding means 33 and is conveyed in the sub-scanning direction indicated by arrow B.

The ink jet recording head 26 is moved in the main scanning direction (A) by the head driving means 34. The paper feeding unit 33 moves the recording paper 32 in the sub-scanning direction (B) orthogonal to the main scanning direction (A).

The control means 35 controls the ink jet printer 44 as a whole, and instructs the head driving means 34 to position the ink jet recording head 26 and the paper feeding means 33 to position the recording paper 32. That is, the control means 35 transmits the pressure control signal 41 to the pressure drive means 39, the head control signal 36 to the head drive means 34, and the paper feed control signal 37 to the paper feed means 33, respectively, and a higher-level device external to the apparatus. The transmitted external signal 40 is converted into a head control signal 36, a paper feed control signal 37, and a pressure control signal 41, which are sent to the head driving means 34, the paper feeding means 33, and the pressure driving means 39, respectively. The pressurization control signal 41 includes, as information, what time, which unit element, which actuator is to be driven, with what magnitude of driving force, and for how long.

In response to the head control signal 36 from the control means 35, the head drive means 34 drives the ink jet recording head 26 so that it is located at a predetermined position at a predetermined time. The paper feed means 33 drives the recording paper 32 so that it is positioned at a predetermined position at a predetermined time in response to the paper feed control signal 37 transmitted from the control means 35. An electric signal, an optical signal, or a wireless signal can be used for the external signal 40, the head control signal 36, the paper feed control signal 37, and the pressure control signal 41.

Each of the piezoelectric elements in the ink jet ejection elements 20a to 20d of the ink jet recording head 26 operates when receiving the pressurization control signal 41 from the pressurizing drive means 39 to apply the ink in the corresponding pressure chamber 12. Then, the ink is discharged from the nozzle communicating with the pressure chamber 12. In this way, by synchronizing the position of the inkjet recording head 26, the position of the recording paper 32, and the application of the pressure control signal 41, an arbitrary position within the printing range of the recording paper 32 can be obtained.
Images, characters and the like can be expressed in a color tone having a desired color and brightness.

As described above, by applying the present invention, it is possible to realize a matrix-shaped array head in which nozzles are arrayed at a high density. Inkjet recording head equipped with high-speed printing,
In addition, it is possible to realize an ink ejection device such as a smaller inkjet printer equipped with an inkjet recording head.

Sixth Embodiment This embodiment is an example in which an ink containing an organic EL element material is used as the ejected ink. In this embodiment example,
By using the substrate for organic EL display as an object to be ejected and coated, by using the inkjet recording head of the present invention, an organic EL display manufacturing element, organic E
An L display manufacturing head and an organic EL display manufacturing apparatus can be configured.

The organic EL display substrate has an upper electrode and a lower electrode on the front surface and the back surface, respectively. For example, PED
When an organic material such as T polyaniline is used as a material for the lower electrode, an ink in which these are dissolved is used and PEDT is formed on the transparent substrate by the above organic EL display manufacturing apparatus.
A pattern can be formed by ejecting an ink in which polyaniline is dissolved.

Other materials that can be discharged and applied by the ink discharge device to form a pattern include, for example,
Electron injection layer material, electron transport layer material, light emitting layer material,
Examples thereof include a hole transport layer material, a hole injection layer material, and an upper electrode layer material. By discharging and applying the materials for the three primary colors, it becomes possible to manufacture an organic display capable of color display.

Seventh Embodiment This embodiment is an example in which an ink containing an organic semiconductor material is used as the ejected ink. In the present embodiment example, by using the substrate for organic semiconductor element as the discharge application target, by using the inkjet recording head of the present invention, the organic semiconductor element manufacturing element, the organic semiconductor element manufacturing head, and the organic semiconductor element manufacturing The device can be configured. In this case, the source electrode and the drain electrode are formed in advance on the organic semiconductor element substrate, and the ink containing the organic semiconductor is ejected by the present ink ejecting device so as to extend over both. Further, after solidification, a gate electrode pattern is formed between the source electrode and the drain electrode.

An insulating layer is formed on the organic semiconductor layer,
A gate electrode is formed on this insulating layer. Alternatively, a gate electrode is formed on the organic semiconductor element substrate, an insulating layer is formed on this gate electrode, and a source electrode and a drain electrode pattern are formed on this insulating layer. Furthermore, an organic semiconductor layer is formed on these using an inkjet recording head. It is also possible to use an organic material for each of the electrodes and the insulating layer, and discharge and apply a solution containing a material for an organic semiconductor by the inkjet recording head to form a pattern.

Examples of organic semiconductor materials include pentacene and
Regioregular poly (3-hexylliophene) or the like can be used. Further, as the organic electrode material, highly doped polyaniline, PEDOT or the like can be used. Various insulating materials can be used as long as they have process compatibility.

In each of the first to fourth embodiments of the present invention, the polyimide resin is used as the damper member, but it goes without saying that the same effect can be obtained with a film-shaped organic compound material. Yes.

The present invention has been described above based on its preferred embodiments, but the ink jet recording head and the ink jet recording apparatus according to the present invention are not limited to the configurations of the above embodiments, and An ink jet recording head and an ink jet recording apparatus in which various modifications and changes are made from the configuration of the embodiment are also included in the scope of the present invention.

[0146]

As described above, according to the present invention,
In addition to realizing a high-density nozzle array in a matrix array head, a simple configuration ensures low cost, sufficient acoustic capacity for multiple branch flow paths, suppresses acoustic crosstalk, and prevents shortage of ink supply. It is possible to obtain an ink jet recording head having a configuration capable of realizing an ink refill operation, and an ink jet recording head including such an ink jet recording head.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing an inkjet recording head according to a first exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an ink jet recording head of the first embodiment example.

FIG. 3 is a plan view showing the ink jet recording head of the first embodiment example.

FIG. 4 is a graph showing the ejection characteristics of the inkjet recording head of the first embodiment.

FIG. 5 is a graph showing the relationship between the plate thickness of the damper member and the acoustic capacities of the nozzles, pressure chambers, and branch channels in the inkjet recording head showing the comparative example of the first embodiment.

FIG. 6 is a graph showing ejection characteristics of an inkjet recording head showing a comparative example of the first embodiment.

FIG. 7 is a plan view showing an inkjet recording head according to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view showing an inkjet recording head of a second embodiment example.

FIG. 9 is a diagram showing the ejection characteristics of the inkjet recording head of the second embodiment.

FIG. 10 is a cross-sectional view showing an inkjet recording head of a third embodiment example according to the present invention.

FIG. 11 is a cross-sectional view showing an inkjet recording head of a fourth embodiment of the present invention.

FIG. 12 is a conceptual diagram showing a main part of an inkjet printer equipped with an ink ejection head according to the present invention.

FIG. 13 is a circuit diagram showing an equivalent electric circuit of the ink jet recording head according to the first to third embodiments of the present invention.

FIG. 14 is a graph for explaining characteristics required for an ink pool.

FIG. 15 is another graph showing the characteristics required for the ink pool.

FIG. 16 is a cross-sectional view showing a main configuration of a conventional ink jet recording head.

FIG. 17 is a plan view showing the main configuration of FIG. 16.

FIG. 18 is a cross-sectional view showing another main part configuration of a conventional ink jet recording head.

FIG. 19 is a perspective view showing a main configuration of FIG. 18.

FIG. 20 is a schematic diagram for explaining movement of a meniscus during a refill operation.

FIG. 21 is a graph diagram for explaining movement of a meniscus during a refill operation.

[Explanation of symbols] 11: Nozzle 12: Pressure chamber 13: Pressure generating means 14: Inlet 15: Branch flow path 16: Main flow path 17: Ink pool 18: Damper member 19: Ink supply port 20: Inkjet ejection element 21: Pressure plate 22: Piezoelectric element 23: Bump 24: Flexible wiring board 25: Ejector plate 26: Inkjet recording head 27: Pool plate 28: Inlet plate 29: Pressure chamber plate 30: Nozzle plate 31: Recess 32: Recording paper 33: Paper feeding means 34: Head driving means 35: Control means 36: Head control signal 37: Paper feed control signal 39: Pressure drive means 40: External signal 41: Pressure control signal 44: inkjet printer 45: Meniscus 46: Ink drop 61: Nozzle forming plate 62: Ink pool plate 63: Aperture forming plate 64: Sealing plate 65: Pressure chamber forming plate 66: Pressure plate 67: Piezoelectric element 68a: upper electrode 68b: lower electrode 69: Ink Pool 70: Communication hole 71: Pressure chamber 72: Ink communication hole 73, 75: Nozzle 74: Ejector array 76: Pressure chamber 77: Ink passage 79: Ink supply groove 80: Communication hole 81: Branch 82: Nozzle plate 83: Distribution plate 84: Cavity plate 85: Pressure plate 86: Piezoelectric element A: Main scanning direction B: Sub scanning direction

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshinori Ishiyama             5-7 Shiba 5-1, Minato-ku, Tokyo NEC Corporation             Inside the company (72) Inventor Shinichi Okuda             5-7 Shiba 5-1, Minato-ku, Tokyo NEC Corporation             Inside the company F term (reference) 2C056 EA01 EA26 FA04 FC01 HA05                       HA19                 2C057 AF06 AF08 AF41 AF79 AF99                       AG14 AP12 AP13 AP23 AP25                       AP34 AP52 BA04 BA14                 2H086 BA59

Claims (15)

[Claims] 1. An inkjet recording head comprising an ink supply port, an ink pool to which ink is externally supplied through the ink supply port, and a plurality of ejectors arranged in a matrix, wherein the ink The pool includes a main flow path communicating with the ink supply port, and a plurality of branch flow paths branched from the main flow path,
Each ejector has a pressure chamber communicating with the branch flow passage, a pressure generating unit for generating a pressure wave in the ink filled in the pressure chamber, and a nozzle for ejecting the ink in the pressure chamber compressed by the pressure wave. An ink jet recording head, comprising: a damper member that is elastically deformed in accordance with a pressure change in the branch flow path, and at least one of the wall surfaces forming the branch flow path. 2. The ink jet recording head according to claim 1, wherein the damper member is formed by one member common to the plurality of branch flow paths. Is wherein the damper member, the acoustic capacitance of the branch channel of one per the ejector c _p, when the sound volume of the nozzle and c _n, satisfies the following equation c _p> 10c _n The inkjet recording head according to claim 1 or 2, characterized in that: Is wherein said damper member, the acoustic capacitance of the branch channel per one said ejector when c _p, the acoustic capacitance of the pressure chamber c _c, satisfy the following equation c _p> 20c _c The inkjet recording head according to claim 1 or 2, wherein 5. The nozzles provided in the plurality of ejectors are provided on one surface of a recording head body, and the damper member is provided on the one surface side. 4. The inkjet recording head according to any one of 4 above. 6. The ink jet recording head according to claim 5, further comprising: a nozzle plate having the nozzle formed therein, the nozzle plate being constituted by the damper member. 7. The ink jet recording head according to claim 6, wherein the nozzle plate has a plate thickness of 20 μm or more and 100 μm or less. 8. The ink jet recording head according to claim 1, wherein the damper member is made of a film-shaped organic compound. 9. The organic compound comprises an acrylic resin, an aramid resin, a polyimide resin, an aromatic polyamide resin, a polyester resin, a polystyrene resin, a nylon resin, or a polyethylene resin. The inkjet recording head according to claim 8. 10. The pressure generating means comprises a piezoelectric element and a pressure plate for transmitting the displacement of the piezoelectric element to the ink in the pressure chamber, and the maximum droplet amount that can be ejected by the pressure generating means is 15 pl or more. Claim 1 characterized by the above.
10. The inkjet recording head according to any one of 9 to 10. 11. The pressure generating means comprising the piezoelectric element and the pressure plate is constituted by a piezoelectric actuator in which the pressure plate is flexibly deformed by expansion and contraction deformation of the piezoelectric element. The inkjet recording head described. 12. The ink jet recording head according to claim 1, wherein the ink comprises a printing ink. 13. The ink jet recording head according to claim 1, wherein the ink contains a material for an organic EL element. 14. The ink jet recording head according to claim 1, wherein the ink contains a material for an organic semiconductor. 15. The ink jet recording head according to claim 1, a first driving unit for moving the ink jet recording head in a main scanning direction, and an ink ejection target for the main scanning. Second drive means for moving in the sub-scanning direction orthogonal to the direction, and control for instructing the first drive means of the position of the inkjet recording head and for instructing the second drive means of the position of the ink ejection target. An inkjet recording apparatus comprising: